Tài liệu Sinh Học

Notochord – stiff dorsal skeletal rod, forms from mesoderm Neural plate  neural tube brain and spinal cord Neurulation – forms hollow dorsal nerve chord Somites – blocks of mesoderm arranged along notochord; sign of segmentation

16 trang | Chia sẻ: huyhoang44 | Ngày: 19/03/2020 | Lượt xem: 1117 | Lượt tải: 0

In 1952, Alfred Hershey and Martha Chase used bacteriophages to show that DNA is the genetic material of T2, a virus that infects the bacterium Escherichia coli (E. coli). Bacteriophages (or phages for short) are viruses that infect bacterial cells. Phages were labeled with radioactive sulfur to detect proteins or radioactive phosphorus to detect...

113 trang | Chia sẻ: huyhoang44 | Ngày: 18/03/2020 | Lượt xem: 1161 | Lượt tải: 0

In 1866, Mendel correctly argued that parents pass on to their offspring discrete “heritable factors” and stressed that the heritable factors (today called genes), retain their individuality generation after generation. A heritable feature that varies among individuals, such as flower color, is called a character. Each variant for a character,...

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Organisms reproduce their own kind, a key characteristic of life. Cell division is reproduction at the cellular level, requires the duplication of chromosomes, and sorts new sets of chromosomes into the resulting pair of daughter cells.

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Autotrophs make their own food through the process of photosynthesis, sustain themselves, and do not usually consume organic molecules derived from other organisms.

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In cellular respiration glucose is broken down to carbon dioxide and water and the cell captures some of the released energy to make ATP. Cellular respiration takes place in the mitochondria of eukaryotic cells.

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Bioluminescence is an example of the multitude of energy conversions that a cell can perform. Many of a cell’s reactions take place in organelles and use enzymes embedded in the membranes of these organelles. This chapter addresses how working cells use membranes, energy, and enzymes.

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Magnification is the increase in the apparent size of an object. Resolution is a measure of the clarity of an image. In other words, it is the ability of an instrument to show two close objects as separate.

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Methane and other compounds composed of only carbon and hydrogen are called hydrocarbons. Carbon, with attached hydrogens, can bond together in chains of various lengths.

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About 25 elements are essential to life. Four elements make up about 96% of the weight of most living organisms. These are oxygen, carbon, hydrogen, and nitrogen. Trace elements are essential but are only needed in minute quantities.

68 trang | Chia sẻ: huyhoang44 | Ngày: 18/03/2020 | Lượt xem: 1110 | Lượt tải: 0